JPH04278680A - Binary image reduction system - Google Patents

Abstract

PURPOSE:To obtain a binary image reduction system that can hold the coupling properties of images. CONSTITUTION:A vicinity setting part 1 obtains an assembly of pixels near the coordinates on the unreduced image information corresponding to the coordinates on the reduced image information in regard of the binary image information. A coupled number counter part 2 obtains the number of coupled pixels of the unreduced image information. Then a pixel value setting part 3 obtains the value of the coordinates set on the reduced image information including the corresponding pixel at the vicinity from the number of coupled pixels. In such a constitution, the coupling properties of images are taken into consideration in a reduction state and therefore the graphic shape is not distorted so much against the change of the image coupling properties.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binary image reduction method that focuses on the connectivity of image information to be processed.

0002

[Prior Art] A conventional binary image reduction method converts the coordinates (x, y) of a pixel on image information after reduction into coordinates (u, v) on image information before reduction, and (u, v)
The coordinates (u, v) are calculated by using a means to find a set of pixels in the vicinity of , and the density of the pixels in the vicinity.
By interpolating the density of the coordinate (u, v), the coordinate (x,
, y).

However, conventional binary image reduction methods do not consider the connectivity of the image when interpolating the density of the coordinates (u, v) on the image information before reduction, so the connectivity of the image changes. The problem is that the shape of the figure is distorted.

0004

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and its object is to provide a binary image reduction method that maintains the connectivity of images.

[0005]

[Means for Solving the Problems] (Means 1) The binary image reduction method according to claim 1 of the present invention is based on image information representing a figure and the background of the figure in binary terms. Even if the value of image information is changed, if the connectivity of the entire image information does not change, it is determined that it can be deleted, or if the connectivity changes, it cannot be deleted. A means for converting (x, y) into coordinates (u, v) on image information before reduction and finding a set of pixels that are in the vicinity of the coordinates (u, v), and coordinates on image information after reduction. The value of the pixel (x, y) is set to the coordinates (u, y) on the image information before reduction corresponding to the coordinates (x, y).
v) means for determining from the value of a pixel p that is an element of a set of neighbors of p and whether the pixel p is erasable or non-erasable;

(Means 2) The binary image reduction method according to claim 2 of the present invention is based on the image information in which a figure and the background of the figure are expressed in binary values, and the coordinates (x . means for selecting a pattern corresponding to a set of pixels that are in the vicinity of coordinates (u, v) on the image information of Regarding the combination of an image pattern corresponding to a set of neighbors of coordinates (u, v) on the image information before reduction corresponding to coordinates (x, y) and an image pattern corresponding to coordinates adjacent to the coordinates (x, y) , and means for making a judgment based on pre-registered values and connectivity.

[0007]

[Operation] Generally, in a binary image, each connected region has its own meaning, so when reducing image information, the connectivity of the image must be maintained. Here, regarding pixels representing figures or backgrounds, pixels whose values do not change the connectivity of the entire image are said to be erasable, and pixels whose values change the connectivity of the entire image are said to be non-erasable. It is known that whether a pixel is erasable or non-erasable can be determined from the number of connections of eight or four neighbors of the pixel. In other words, pixels whose number of connections is 1 can be deleted, and no matter what value they take, the connectivity of the image remains unchanged.

In the binary image reduction method of the present invention, the value of a pixel having coordinates (x, y) on the image information after reduction is as follows:
The determination is made based on the value of a set of pixels in the vicinity of the coordinates (u, v) on the image information before reduction corresponding to the coordinates (x, y) and the connectivity of the set of pixels in the vicinity. In the binary image reduction method according to the first aspect, the value and connectivity of a set of pixels in the vicinity are determined from the value of a pixel p that is an element of the set and the connectivity of the pixel p. In the binary image reduction method according to claim 2, instead of examining the values and connectivity of a set of pixels in the vicinity, the image pattern corresponding to the set of pixels in the vicinity and the The determination is made by examining combinations of image patterns corresponding to sets adjacent to the set. Specifically, regarding the combination,
The coordinates (x,
y).

According to the configuration of the present invention, the coordinates (x, y
), it is possible to reduce the image information so that there is little change in the connectivity of the entire image information.

0010

Embodiment (Embodiment 1) FIG. 1 is a block diagram in Embodiment 1 of the present invention. Regarding binary image information in which pixels that are figures are expressed as 1 and pixels that are background are expressed as 0,
The connection number counting unit 2 calculates the number of connections for pixels whose value is 1 based on 8 connections, and the number of connections for pixels whose value is 0 based on 4 connections. The neighborhood setting unit 1 converts the coordinates (x, y) of a pixel on the image information after reduction into the coordinates (u, y) on the image information before reduction.
v) to find a set of pixels near the coordinates (u, v). The pixel value determining unit 3 determines the coordinates (u
, v) and whether the pixel is erasable or non-erasable, the coordinate (u
, v) on the reduced image information (x, y)
Determine the value of the pixel.

FIG. 2 is a flowchart in the first embodiment of the present invention. The connection number counting section 2 counts the pixel values and the number of connections on the image information before reduction (1), and outputs the result of counting for all pixels to the pixel value determination section 3 (2). The neighborhood setting unit 1 calculates the coordinates (u, v) on the image information before reduction that correspond to the coordinates (x, y) on the image information after reduction, and selects a pixel near the coordinates (u, v). (2) Outputs the information to the pixel value determination unit 3. The pixel value determination unit 3 determines the value of the pixel at coordinates (x, y) according to the following (1) to (6) from the values of neighboring pixels and the number of connections.

(1) When the neighborhood includes a pixel with a value of 1 and does not include a pixel with a value of 0, the coordinate (
The value of the pixel (x, y) is 1.

(2) When the neighborhood includes a pixel with a value of 0 but does not include a pixel with a value of 1, the coordinate (
x, y) pixel value is 0.

(3) When the neighborhood includes a pixel with a value of 1 and a connection number of 1, but does not include a pixel with a value of 0 and a connection number of 1, the value of the pixel at coordinates (x, y) is 0.

(4) When the neighborhood includes a pixel with a value of 0 and a number of connections of 1, but does not include a pixel with a value of 1 and a number of connections of 1, the value of the pixel at coordinates (x, y) is 1.

(5) When the neighborhood includes a pixel with a value of 1 and the number of connections of 1, and a pixel with a value of 0 and the number of connections of 1, the value of the pixel at such coordinates (x, y) is tentatively 1, find the number of connections of the pixel at the coordinates (x, y), and if the number of connections is 1, the value of the pixel at the coordinates (x, y) is 0; if it is not 1, the value of the pixel at the coordinates (x, y) is The pixel value is 1.

(6) When the neighborhood does not include a pixel with a value of 1 and the number of connections of 1, and does not include a pixel with a value of 0 and the number of connections of 1, calculate in the same way as in case (5).

(Embodiment 2) FIG. 3 is a block diagram in Embodiment 2 of the present invention. An example of converting binary image information in which pixels that are figures are expressed as 1 and pixels that are background as 0 is converted into image information after reduction, in which the image information before reduction is reduced by half in both the vertical and horizontal directions. Then, the pattern determining unit 4 divides the unreduced image information into rectangles of 2 pixels vertically by 2 pixels horizontally, and selects a pattern corresponding to each rectangle from pre-registered image patterns. The combination confirmation unit 5 checks the pixel p on the reduced image information.
Confirm the combination of the image pattern corresponding to the rectangle on the unreduced image information corresponding to the pixel p and the image pattern corresponding to the pixel q on the unreduced image information adjacent to the pixel p, and connect the combination regarding the combination. A value given in advance in consideration of the nature of the pixel p is set as the value of the pixel p.

FIG. 4 is a flowchart in a second embodiment of the present invention. The pattern determination unit 4 divides the image information before reduction into rectangles of 2 pixels vertically by 2 pixels horizontally, selects a pattern corresponding to each rectangle from the image patterns registered in advance, and selects a pattern corresponding to all the rectangles. When selecting , information about the image pattern selected for the image information before reduction is output to the combination confirmation section 5. The combination confirmation unit 5 identifies an image pattern corresponding to a rectangle on the image information before reduction that corresponds to pixel p on the image information after reduction, and a pixel q on the image information before reduction that is adjacent to the pixel p. Based on the combination with the image pattern, determine the value of pixel p according to the following (1) to (3).

(1) If the image pattern corresponding to the pixel p is shown in (a) to (g) in FIG.
No matter what image pattern corresponds to pixel q adjacent to , the value of pixel p is 1.

(2) If the image pattern corresponding to the pixel p is from (h) to (k) in FIG.
If the image pattern corresponding to the pixel q adjacent to the direction indicated by the circle in the figure is from (a) to (g) in FIG. 5, the value of the pixel p is 1, or the image pattern corresponding to the pixel q is 5 (h) to (p), the value of pixel p is 0.

(3) If the image pattern corresponding to the pixel p is from (l) to (p) in FIG.
No matter what image pattern corresponds to pixel q adjacent to , the value of pixel p is 0.

[0023] Here, we have described the case where the image pattern is reduced to one-half both vertically and horizontally, but when the image pattern is reduced to one-third or more, or when the ratio of vertical and horizontal reduction is different, the image pattern If we give in advance a value that takes connectivity into account for the combination of
Binary images can be reduced in the same way.

Further, the density is utilized in the binary image reduction method described in the first or second embodiment. The density counting unit 6 uses two threshold values a and b (a≦b) to calculate the value of a pixel that is an element of a set that is a neighborhood in the first embodiment.
In the second embodiment, if the density c of the coordinates (u, v) on the image information before reduction, which is obtained by interpolation from the values of pixels included in the rectangles obtained by dividing the image information, is c<a, then the coordinates (u , v) on the reduced image information corresponding to the coordinates (x,
If the pixel value of y) is 0, and c>b, the corresponding coordinates (x,
Let the value of pixel y) be 1. Further, if a≦c≦b, the value of the pixel at the coordinates (x, y) corresponding to the coordinates (u, v) is determined by the pixel value determination unit 3 in the first embodiment.
However, in the second embodiment, the combination confirmation unit 5 decides.

[0025]

[Effects of the Invention] As described above, according to the present invention, regarding image information representing a figure and the background of the figure in binary,
For a pixel with coordinates (x, y) on the image information after reduction, find a set of pixels that are in the vicinity of coordinates (u, v) on the image information before reduction that correspond to the coordinates (x, y). and means for determining the value and connectivity of the neighborhood from the value of a pixel p that is an element of a set of pixels in the neighborhood and the connectivity of the pixel p, or determining the value and connectivity of the neighborhood. A means for determining the combination of an image pattern corresponding to a set of pixels in the vicinity and an image pattern corresponding to a set adjacent to the set from values given in advance by considering connectivity, By configuring a binary image reduction method that maintains connectivity, there is an effect that distortion of figures due to changes in image connectivity is reduced. In addition, high-speed processing is possible by using a means to interpolate the density of the coordinates (u, v) by using the density of pixels near the coordinates (u, v) on the image information before reduction. effective.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first embodiment of a binary image reduction method of the present invention.

FIG. 2 is a flowchart showing the operation of the first embodiment of the binary image reduction method of the present invention.

FIG. 3 is a block diagram showing a second embodiment of the binary image reduction method of the present invention.

FIG. 4 is a flowchart showing the operation of a second embodiment of the binary image reduction method of the present invention.

FIG. 5 is a diagram showing an image pattern used in Example 2 of the binary image reduction method of the present invention.

[Explanation of symbols]

1 Neighborhood setting section 2　Connection number counting section 3 Pixel value determination section 4 Pattern determination section 5 Combination confirmation section 6 Concentration counting section

Claims (3)

[Claims] Claim 1: Image information representing a figure and the background of the figure in binary values can be erased if the connectivity of the entire image information does not change even if the value of a certain pixel is changed. Or, if the connectivity changes, the pixel coordinates (x, y) on the image information after reduction are changed to the coordinates (u, y) on the image information before reduction.
v) to obtain a set of pixels in the vicinity of the coordinates (u, v); and a means for converting the coordinates (u, v) into
x, y), the value of the pixel p that is an element of the set of neighbors of the coordinates (u, v) on the image information before reduction corresponding to the coordinates (x, y), and the pixel A method for reducing a binary image, comprising: means for determining whether p is erasable or non-erasable. Claim 2: For image information that expresses a figure and the background of the figure in binary values, coordinates (x, y) of a pixel on the image information after reduction are converted to coordinates (u, v) on the image information before reduction.
means to calculate a set of pixels in the vicinity of the coordinates (u, v), and a means to calculate the pixels in the vicinity of the coordinates (u, v) on the image information before reduction from a pre-registered image pattern. means for selecting a pattern corresponding to the set;
The value of the pixel at the coordinates (x, y) on the image information after reduction corresponds to the set of neighbors of the coordinates (u, v) on the image information before reduction that correspond to the coordinates (x, y). A binary image system comprising: an image pattern; and means for determining a combination of an image pattern corresponding to coordinates adjacent to the coordinates (x, y) from pre-registered values and connectivity. Reduction method. [Claim 3] Coordinates (u, v) on image information before reduction
Using the concentration of pixels in the vicinity of , the coordinates (u
, v), and from the density of the coordinates (u, v), calculate the possibility of erasing the pixel at the coordinates (x, y) on the reduced image information corresponding to the coordinates (u, v). Claim 1 or Claim 2 characterized in that it consists of means for determining.
The described binary image reduction method.